Modern motor vehicles are equipped with a vast array of electronic circuitry to manage operation of the vehicle and to ensure the safety of occupants in the case of an accident. For example, the use of airbags is now common and airbag systems require sophisticated electronics to monitor the motion of the motor vehicle to ensure that the airbags are properly deployed, and deployed in an appropriate manner to provide protection in a given accident situation. Furthermore, so called active safety systems such as adaptive cruise control systems, forward collision warning and braking systems, blind spot monitoring systems, and lane departure warning systems are becoming increasingly common and all require sophisticated electronic circuitry. A modern motor vehicle therefore includes a significant number of electronic control units (ECUs).
In the environment of a motor vehicle, it is important for ECUs to be adequately sealed in order to prevent environmental influences (such as the ingress of water, dust etc.) from affecting ECU performance. Additionally, it can be advantageous in many installations to ensure that ECUs provide good heat dissipation from their internal circuit boards, and to ensure that the circuit boards are securely retained in position, noting that there are usually very considerable vibrations occurring during operation of a motor vehicle.
Additionally, motor vehicle manufacturers are continuously striving to reduce the componentry of their vehicles, which means that producers of various electronic systems for installation in motor vehicles are generally striving to reduce the cost involved in their production, and to simplify their production.
It is an object of the present invention to provide an improved electronic control unit, which may be suitable for use in a motor vehicle.
According to the present invention, there is provided an electronic control unit having a housing containing a circuit board, wherein the housing comprises a base and a cover between which the circuit board is located, the unit being characterised in that the base and the cover are inter-engaged via an interference fit connection extending around at least a major part of a peripheral edge of the cover.
Preferably, the interference fit connection involves elastic deformation of said cover around its peripheral edge.
Advantageously, the cover is resiliently deformable.
Conveniently, the peripheral edge of the cover engages an inwardly directed surface of the base.
Advantageously, the peripheral edge of the cover is received within a groove formed around the base as a snap-fit.
Optionally, the groove is formed around the inwardly directed surface.
Preferably, the circuit board is clampingly engaged between said base and said cover.
Conveniently, a first side of the circuit board contacts the base, and an opposing second side of the circuit board contacts the cover.
Advantageously, the first and second sides of the circuit board respectively contact the base and the cover around a peripheral region of the circuit board.
Preferably, the second side of the circuit board contacts a re-entrant region of the cover which is depressed inwardly of the base.
Conveniently, the re-entrant region of the cover is spaced inwardly of the peripheral edge of the cover.
Advantageously, the unit further comprises a peripheral seal adjacent the interference fit inter-engagement.
Preferably, the seal extends around the circuit board, and is located between the peripheral edge of the cover and the re-entrant region of the cover.
Conveniently, both the base and the cover are formed of heat conductive material.
Advantageously, at least a major part of the peripheral edge of the cover is rounded.
Optionally, the peripheral edge of the cover has a shape comprising rounded corners.